I. Field of the Invention
The present invention relates generally to antennas and, more particularly, to microwave antennas.
II. Description of Material Art
There are many previously known microwave antennas, i.e. antennas for emitting electromagnetic radiation in the millimeter wavelength range. For example, a narrow bandwidth around 77 gigahertz is reserved for automotive use.
These previously known microwave antennas typically comprise an electromagnetic radiator array constructed of a plurality of electrically conductive radiator patches disposed on one side of a nonconductive substrate. An input feed line containing the signal is then electrically connected to one end of the array through a power divider network so that typically each row in the radiator array receives the same amount of power from the feed line.
Ideally, each connection in the power divider network forms a perfect impedance match, e.g. 50 ohms. When such a perfect impedance match is obtained in the power divider network, essentially all of the power from the input feed line is electrically coupled to the radiator array.
Unfortunately, the previously known power divider networks for microwave antennas do not achieve a perfect impedance match at each connection in the power divider network since the power divider network necessarily requires curves which alter the impedance of the power divider at each of its connection points. The impedance mismatch in the power divider network, in turn, results in spurious radiation which can cause undesired cross talk or coupling into the main radiator array.